Alternating-current dynamo-electric machine.



L. DREYFUS @L -F. HILLEBRAND.

ALTERNATING CURRENT DYNAMO ELECTRIC MACHINE.

APPLICATION FILED SEPT. 4, 1912.

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. APPLICATION FILED SEAPT. 4, 1912. 1,1 1 5,289. Patented 001.27, 1914.

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UNITED sTATEs PATENT oEEICE.

LUDWIG DREYFUS AND FRANZ HTLLEBEAND, oF NIEDEnsCHNHAUsEN, GERMANY,AssIeNoEs To GENERAL ELECTRIC COMPANY, A CORPORATION o'E NEW YORK.

ALTERNATING-CURRENT DYNAM-ELECTRIC MACHINE.

Speeication of Letters Patent. .Patented Oct. 27,1914.

Application led September 4, 1912. Serial No, 718,504;

To all .whom ttmay concern.'

Be it known that we, LUnwIG DREYFUS,

asubject of the King of Great Britaingand FRANZ HILLEBEAND, a subject ofthe King of 1russia,residingl at Niederschnhausen, Germany, haveinvented certain new and useful Improvements in Alternating-CurrentDynamo-Electric Machines, of which' winding are connected in series, thefields produced bythe armature and field wind-l ing are opposed to eachother in phase and thus substantially neutralize each other.

If it is attempted to operate such a ma chine as a motor, it will not becapable of producting anygtorque at starting, or if Voperated as agenerator it will not produce any voltage. I

Our invention has for its object to change such a dynamo electricmachine into an operative one having a shunt characteristic in a noveland simple manner, and also to control the speed of a machine of thistype when operated as a motor. In accordance with our invention, wecreate an exciting field for -such a machine by shifting the phase ofthe current `winding by means of 'a synchronous motor connected in shuntto the armature.

Other features of our invention will be pointed out with particularityin the claims annexedto and forming fication.

For a better understanding of our invention, reference Inay be had tothe following descriptiontakenv in connection with the accompanyingdrawings, in which- Figure 1 shows diagraininatically a threephasecommutator motor arranged inr'ac'- coi-dance with our invention; Fig. 2is an explanatory diagram; Fig. 3 shows a modification .of the motor ofFig. l; and Fig. 4 shows a regulating mechanism for the inotor of Fig.1.

in the compensating part of this s'peci-v Like letters of reference willbe used throughout this specification `and the drawings to indicatesimilar parts.

Referring to the drawings, l is the compensating winding on thestationary member of a three-phase commutator motor and 2 is the rotarymember or armature pro- -vided with a 'cominutator 3 on which brushes 4bear. The compensating winding` is connected to the brushes 4 eitherdirectly or through a transformer so as to be in series with thearmature. In order to change such a motor into one having a shuntcharacteristic, or, 'in other words, to' control its speed, we connect asynchronous motor 12 in shunt to the brushess of the alternating currentcommutator motor. By using' a synchronous motor in this way it ispossible to regulate the alternating current coniniutator.',motor byregulating the field of theusyncnronous motorend conse-4 quently theregulating devices become quite siiiiplegas does also thc transitionfrom operationi above synchronism to that below synchronisnr 4If eachphase of the compensating winding l is directly in. line with thecorresponding brush Li, by which we mean the arn'iaturereacti on isequal and opposite in phase to the field produced by the compensatingwinding when the saine cur- 'rcnt iiows in both the armature andconipensating winding, the apparent reactance of the alternating currentwinding of the 4synchronous motor will shift the phase of the current inthe compensating winding relatively to that in the armature to create'an exciting field. l If I, represents the current in the compensatingwinding, W, the number of turns in the compensating winding, l, thearmature current, lV., the number of armature turns which are consideredas negative since vthey should be connected in opposition to thepositive turns W1 of the compensating winding and'I2 the .current in thealternating Acurrent winding of synchronous motor 12, which we haveillustrated as lagging, then, as shown in Fig. 2, I, and I2, or thecorresponding ampere turns 1 W', and I2 W, include an angle whichcorrespondsto the creation of mechanical torque, and Le W, representsthe exciting ampere turns. If the vector E in Fig. 2 represents thesupply voltage, then neglecting the fall of potential in consequence ofleakage and ohmic resistance, the sum of the voltages E, and. E, indupedin. the compensating Winding and in the armature,y respectively, isequal to the supply voltage E.

By varying the excitation of the synchronous motor 12, it is possible tovary the apparent reactance ci its alternating current Winding at will.llt the field Winding 13 of the synchronousmotor 12 is not eX- cited atall, or is under` excited, the syn chronous lmotor acts like aninductive loadas is well known. With the eld, Winding 13 over-excited onthe contrary, the-,synchronous meter receives leading current., When thesynchronous motor acts as an inductive load, the' commutater motor willoperate at over synchronous speed, and when the synchronous motor`receives leading current, the commutator motor Willl-run undersynchronous speed. It will 'thus be seen that by regulating the field othe 'synchronous motor, the speed of the commutator motor can be: variedat will. However, the conditions must be such that the synchronous motor12 can never fall outlet step even'ivhen its terminal voltage is verysmall which will be the case when the commutator motor is passingthrough synchronism.- In order tol keep the synchronous motor in step,We previde a second synchronous motor 14; which is coupled withsynchronous motor 12 either directlyA er indirectly lby means of acoupling Witha constant ratio of-transmission. The use of the secondsynchronous motor 14 is advantageous because the power 'factor of thethree-phase commutator motor 1s entirely controlled by the angle-atwhich the rotors of the two synchronous motors '12 and la are coupled,but since the mostv advantageous angle of coupling is dependent upon thespeed of the commutator motor, it s necessary, in order to alwaysoperate it under the most favorable conditions, to relatively change thephase relation of the voltages of the synchronous motors hy means ofeither a rotatable coupling or to arrange the -statorslof the tvvosynchronous motors so as te be capable of beingdisplaccd relative toeach other. The same result may also be obtained electrically. In thearrangement of Fig. 1, we have shown the ield Winding of the motor 14divided into two parts 15 and 16 displaced with relation to each otherso that by varying the excitation of either one or beth of the sections15 and 16, the phase of the voltage tor-16 is shifted relatively to thatofthe synchronous motor 12. Anothermthod of shifting the phase angle ofthe voltages` of the motors 12 and 14 is shown in'pFig. 3, in which apotential regulator 17 is connected between the source of supp yand thesynchronous motor 1 4, and a' regulable transformer 1() between thebrushes 4 ofthe commutator motor and the synchronous'motor of thesynchronous mo#l l12. 'l`he direct current excitation vfor thesynchronous .motors 12 and. le maybe taken from .a battent laasshown inEig. 1, or any other suitable'tource of direct current, as, for;lltancone of the synchronousmotors may be constructed as a Vrotaryconverter as shown in Fig. 3. I

l The speed of avpolyphase commutator mntor of the'type described above,decreases Whenloadis thrown on it and changeswith variations intheperiodicity of the sup `y voltage, as-does any polyphase shunt me or.This lis often satisfactory withfcertain classes ofwwork., but forbotherclasses of Work it lis desirable vthatethe speedjof` the driving :annitor does not vary with fluctuations-in load, etc. .By means of aregulator, the speed :of theY polyphasel commutator motor may. be heldconstant notwithstanding variations .in loadin the supply volta e,.orinthe periodicity of thesupplyvo aga. In'Fig..r4

themotor .of Fig. 1. ln .this li'z'ugure,l a. small dynamo 2O isconnected to the shaft 21 of the commutator A.A1notor,f..audconsequently; its voltage is proportional tolthe speed ,eithecommutatormotor.. .The eld of thedynanio,

arms otwhichiis connectedto .thearms of rheostats 23 and 24;, whichrheostats are connected in the held windings 13 and 1G of synchronousmotors12 andl le, respectively. 'lhese rheostats are adjusted toobtainthe proper ne load speed or". the commentator4 mo.- tor, so thatlwhen adjusted, thedynamo20 generatesconstant potential. y As l explainedabove,l in `order to maintain the .speed-,of the"commutator,,motoncenstant as its load varies, it is necessary .to .varythe field of the .synchronous motor 12. We proferably provide it with atieldwinding AWound..differentially with .respect to the Winding 13..`The winding 25, with current from a small exciter. 26, driven atconstant speed by the synchronous motors 12 and 14. Thearmature` of,this exciter is connected to the coil 27 of a Tirrill regulator (showndiagrammatically)- vand thev armaturegof thedynamo 20 is connected tothecoil 29 of the regulator. The contacts 30 of the regulatbr .open andclose a short circuit about `26.. .As the commutator' motor varies inspeed, the 2O varies, allovgi'ng thecontacts. 30 tol be @losed oropenedhfor a longer. time, thusfthe lield of exciterr26 is yvaried andconsequently the voltage generated by it and Ithestrengrth of thedilerential eld Windingy is also varied, which inturnvaries theresultantthe speed of the polyphase cpmmutator'mo-- torconstant. If desired,theTirrill rV ula` tor may bel over or under compounde by means of acurrent coil 32. If this'coilover we havesliovvn aregulator mechanismiorvoltage generated bythe dynamo field of the synchronous motor tomaintain 20 is yvaried by means o a. rheostatr22,` the M is;Y suppliedtherheostat 31 in the field circuit of exciter compounds, then withincreasing load or with the falling of the'voltage or the periodiclty ofthe supply, the regulator will operate t o decrease the s eed of thecommutator motor, but with sud en variations in load, it will adjustitself to the new condition of stability with precision and withoutoscillations. Ifthe coil 32 under-compounds, the regulator will operateto increase the speed of the commutator motor.

We have used the term connected to throughout the specification andclaims to mean either a direct connection, or an indirect connection bymeans of transformers, and we aim in the claims, hereto appended, tocover such a modification as well as anyother modifications which do notinvolve a departure from the spirit and scope of our invention.

What we claim .as new and desire to secure by Letters Patent of theUnited States, is,-

1. In a polyphase alternating current dynamo electric machine, anarmature provided with a commutator and brushes, a polyphasecompensating winding connected to'said brushes, a synchronous motorconnected in shunt to said brushes, and means for driving saidsynchronousmotor at synchronous speed. A

2. In a polyphase alternating current t dynamo electric machine, anarmature pro- :Correct 'vJded with a commutator and brushes, a

`polyphase compensating winding connected to, said brushes, asynchronous motor connected in shunt to said brushes, anda secondsynchronous motor for driving said first mentioned synchronous motor atsynchronous speed.l

3. In av polyphase alternating current dynamo electric machine, anarmature provided with a commutator and brushes, a polyphase compensatinwinding connected to said brushes, a sync ronous motor connected inshunt to said brushes, a second synchronous motor for driving said firstmentioned synchronous motor at synchronous speed, and means forrelatively changing the phase relation of the voltages of saidsynchronous motors.

4. In al polyphase alternating current dynamo electric machine, anarmature provided with a commutator and brushes, a polyphasecompensating Winding connected to said brushes, a synchronous motorconnected in shunt to said brushes, means for varying thefieldexcitation of said synchronous motor, and means for driving saidSynchronous motor at synchronous speed.

5. In a polyphase alternating current dynamo elect-ric machine, anarmature provided with a commutator and brushes, a polyphasecompensating winding connected to said brushes, a synchronous motorconnected in shunt Ito said brushes, means for varying the fieldXcitation of said synchronous motor, and second synchronous motor fordriving said rst mentioned synchronous motor at synchronous speed.'

6. In a polyphase alternating current dynamo electric machine, anarmature provided with a commutator and brushes, a. polyphasecompensating winding connected to said'brushes, a synchronous motorconnected in shunt to said brushes, means for varying the fieldexcitation of said synchronous motor, a second synchronous motor fordriving said first mentioned synchronous motor at synchronous speed, andmeans for relatively changing the phase relation of the voltages of thesynchronous motors.

In witness whereof, we have hereunto set our hands this 20th day ofAugust, 1912.

LUDWIG DREYFUS. `FRANZ HILLEBRAND.

Witnesses:

RICH. NroKLAUs, FRITZ W. Bnn'rsom R. F. W HIT-EHEAD, l

.Acting Commissioner of Patents.

It is hereby certified that in Letters `Patent No. 1,115,289, grantedctcber 27, i; 1914,' upon the application of LudwigDreyfus and FranzHillebrand, of Nieder- :E schnhausen, Germany, for an improvement inAlternating-Current Dynamo- Electric Machines, erro-rs appear in theprinted specification requiringvcorre'ction as follows: Page l, line 27,for the word 4producting read producing; same page, 100, for thereference-letter L read L2; 4and that the said Letter:-l Patent shouldbe read with these corrections therein that the samel may conform to the,record of the me in the Patent ofae. l l i -lSigned and sealed this17th day of November, A, 1914:.`

